Percutaneous transluminal coronary angioplasty (PTCA) and stenting are therapeutic medical procedures used to increase blood flow through the coronary arteries and can often be used as alternatives to coronary bypass surgery. In PTCA procedures, the angioplasty balloon is inflated within the stenosed vessel, at the location of an atheroma or plaque deposit, in order to shear and disrupt the wall components of the vessel to obtain an enlarged lumen. Stenting involves implanting an endoluminal prosthesis in the vessel to maintain patency following the procedure. In order to initiate these procedures, one must first introduce a guide wire into the lumen of the vessel to serve as a conduit for other interventional devices, such as angioplasty balloons and stent delivery systems. This guide wire must be advanced into a position past the location of the atheroma or plaque deposit.
In some cases, a vessel may be totally occluded, and even a guide wire cannot be introduced. This condition is referred to as a chronic total occlusion. In order to advance the guide wire across a calcified, tough and resistant lesion it is necessary to “deep seat” the guide catheter. Often when the physician is trying to get the wire across a tough lesion, the guide will back out of its position in the aortic arch by the force applied to the wire. Undesirably, these situations cause trauma that physicians would like to avoid. In addition, it has been recognized that proper positioning of the guide wire relative to the center of the occlusion is important because, depending upon the configuration of the occlusion, the tip of the guide wire has a natural tendency to be directed toward the side of the occlusion rather than the center. This can result in vessel perforation, dissection and inability to cross the occlusion.
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